Systems and methods for digital laser projection with increased contrast using fourier filter

Abstract

An optical filter to increase contrast of an image generated with a spatial light modulator includes a lens for spatially Fourier transforming modulated light from the spatial light modulator, and an optical filter mask positioned at a Fourier plane of the lens to filter the modulated light. The modulated light has a plurality of diffraction orders, and the optical filter mask transmits at least one of the diffraction orders of the modulated light and block a remaining portion of the modulated light. A method that improves contrast of an image generated with a spatial light modulator includes spatially Fourier transforming modulated light from the spatial light modulator onto a Fourier plane, and filtering the modulated light by transmitting at least one diffraction order of the modulated light at the Fourier plane and blocking a remaining portion of the modulated light at the Fourier plane.

1 . A projection system for projecting a video, comprising:
 a plurality of laser light sources, each producing light of a different respective primary color;   a plurality of digital micromirror devices, wherein each of the digital micromirror devices is configured to receive and modulate light from a different one of the laser light sources, wherein each of the digital micromirror devices comprises a two-dimensional rectangular array of micromirrors that lie in a plane having a normal, wherein each of the digital micromirror devices is configured to receive light from its associated laser light source at a non-zero angle relative to the normal of its plane, wherein each micromirror is configured to be tilted to an ON angle and to an OFF angle, and wherein each micromirror is configured to tilt between the ON and OFF angles multiple times per image frame;   a beam combiner configured to combine the modulated light from the plurality of digital micromirror devices; and   projection optics, wherein the projection optics comprises:
 a Fourier lens configured to spatially Fourier transform the modulated light from the beam combiner; 
 an optical filter mask positioned at a Fourier plane of the Fourier lens; and 
 a projection lens configured to project the modulated light from the beam combiner as filtered by the optical filter mask onto a diffusely-reflective screen such that the video is viewable by multiple observers.